Method and systems for improving the operation of transmissions for motor vehicles

ABSTRACT

Methods and systems for improving the operation of transmissions for automotive vehicles increase the main line fluid pressure of a “factory installed” transmission to permit shifting of gears at proper time intervals without undesireable side effects including late or delayed shifts. The hydraulic circuitry of a “factory installed” automotive transmission is also modified to increase the accumulator range to improve the quality of a “1-2” shift, and to extend the useful operating life of the transmission. A seal assembly is provided for reducing leakage of transmission fluid, and additional modifications to the hydraulic circuitry of the automotive transmission provide a smooth, quick and positive forward clutch apply circuit, and increase the servo-apply pressure to the intermediate and overdrive servos to increase the holding capacity of the second and fourth bands and to adjust the field of the shift.

This application is a divisional of U.S. patent application Ser. No.09/796,017, filed Feb. 28, 2001, and entitled “Methods And Systems ForImproving The Operation Of Transmissions For Motor Vehicles”, whichclaims the benefit of U.S. Provisional Application Ser. No. 60/186,836,filed Mar. 3, 2000, U.S. Provisional Application Ser. No. 60/186,835,filed Mar. 3, 2000, and U.S. Provisional Application Ser. No.60/196,067, filed Apr. 10, 2000.

BACKGROUND OF THE INVENTION

The methods and systems of the present invention are directed to themodification and improvement of transmissions for automotive vehicles ofthe type installed by original equipment manufacturers. Suchtransmissions are commonly referred to as “factory installed”, and thisterminology will be adopted in the following discussion. The inventionis particularly directed to the improvement and modification ofautomotive transmissions commonly known as TFOD-DSL which are installedin vehicles produced by Chrysler Motor Corporation, RE4R01A installed invehicles produced by Mazda Motors Corporation, and 4R44E/4R55E installedin vehicles produced by the Ford Motor Corporation.

The present inventor owns U.S. Pat. No. 4,449,426 issued on May 22,1984; U.S. Pat. No. 4,711,140, issued on Dec. 8, 1987; U.S. Pat. No.4,790,938, issued on Dec. 13, 1988; U.S. Pat. No. 5,253,549, issued onOct. 19, 1993; U.S. Pat. No. 5,540,628, issued on Jul. 30, 1996; U.S.Pat. No. 5,624,342, issued on Apr. 29, 1997; U.S. Pat. No. 5,730,685,issued on Mar. 24, 1998; U.S. Pat. No. 5,743,823, issued on Apr. 28,1998; U.S. Pat. No. 5,768,953 issued on Jun. 23, 1998; U.S. Pat. No.5,820,507 issued on Oct. 13, 1998; U.S. Pat. No. 5,967,928 issued onOct. 19, 1999; U.S. Pat. No. 6,099,429 issued on Aug. 8, 2000; U.S. Pat.No. 6,117,047 issued on Sep. 12, 2000. The disclosures of these patentsare expressly incorporated by reference herein.

In the factory installed TFOD-DSL automotive transmission Applicant hasrecognized that when this transmission is subjected to severe operatingconditions, it lacks the necessary torque capacity to prevent slippingof gears. Although an increase in mainline pressure will correct theslipping, merely increasing the line pressure will result in undesirableside effects such as late shifting or no upshifting under wide openthrottle conditions.

With regard to the factory installed RE4R01A automotive transmission,Applicant has recognized that modification of the hydraulic circuitry ofthis transmission can extend the range of accumulator pressure fromabout 70 psi to 150 psi or greater. Extending the range of accumulatorpressure will result in improvement to the quality of the “1-2” shiftand also will extend the operating life of the transmission. Applicanthas also recognized that the seal assembly of the RE4R01A automotivetransmission is arranged in a manner in which leakage of transmissionfluid can occur during operation of the transmission resulting in clutchplate slippage which adversely affects the operation of thetransmission.

With regard to the 4L44E/4R55E automotive transmission, Applicant hasrecognized that forward movement of the vehicle relies upon severaldifferent cooperating components including a power train control module,an EPC (electronic pressure control) solenoid for regulating pressure,and the ability of a forward modulator valve to regulate a forwardengagement control valve. The failure of any of these components of thisautomotive transmission can result in loss of forward movement of thevehicle.

It is the object of the present invention to eliminate theaforementioned disadvantages of the known factory installed automotivetransmissions. In particular, the primary objects of the presentinvention include increasing the main line pressure of the factoryinstalled TFOD-DSL automotive transmission without resulting in theundesireable side effects including late shifts and no upshifts duringwide open throttle conditions; modifying the hydraulic circuitry of thefactory installed RE4R01A automotive transmission to extend the range ofaccumulator pressure from 70 psi to 150 psi or greater for improving thequality of the “1-2” shift and for extending the useful life of theautomotive transmission; improving the sealing assembly of the factoryinstalled RE4R01A automotive transmission to prevent leakage of fluidand slippage and burnout of the clutch plate; modifying the hydrauliccircuitry of the factory installed 4R44E/4R55E automotive transmissionfor providing a smooth, quick and positive forward clutch apply circuitthat is reliable and controlled exclusively by movement of the shiftcontrol lever, and increasing the servo apply pressure to theintermediate and overdrive servos for increasing the holding capacity ofthe second and fourth gear bands and for providing means for adjustingthe feel of the shift (e.g., softer or firmer) to suit the needs of aparticular driver or vehicle.

Other objects and advantages of the present invention will becomeapparent to those skilled in the art from the following discussion.

SUMMARY OF THE INVENTION

In a first aspect of the present invention, a factory installed TFOD-DSLautomotive transmission is modified to increase the main line pressurefrom a maximum of approximately 95 psi to 120 psi or greater byreplacing the original pressure regulator spring to exert an increasedresilient force on the pressure regulator valve. The regulator valvefeeds main line pressure to the throttle valve, and when the throttlevalve is opened mechanically, the throttle pressure corresponds to themain line pressure. By increasing the resilient force applied by thepressure regulator spring to the pressure regulator valve, the throttlepressure is increased, thereby increasing main line pressure. Increasingthe main line pressure increases the torque capacity of the transmissionwhich tends to prevent slipping of gears and soft shifts. However, inorder to avoid undesirable side effects of increased pressure includinglate shifts or no upshift during wide open throttle, the size of thethrottle valve is adjusted (decreased) to avoid direct contact betweenthe throttle valve and a kickdown valve at above approximately ⅞th ofwide open throttle operation. By avoiding direct contact between thekickdown valve and the throttle valve above ⅞th throttle condition, thethrottle valve is not opened mechanically by the kickdown valve, butinstead, the throttle valve spring continues to regulate both thethrottle pressure and the corresponding main line pressure through wideopen throttle. In this manner, the undesirable side effects of increasedmain line pressure, including late shifts and no upshift at wide openthrottle, are avoided.

In a further embodiment of the present invention, the hydrauliccircuitry of the factory installed RE4R01A automotive transmission ismodified to increase the accumulator pressure from approximately 70 psito approximately 150 psi or greater. Extending the pressure range of theaccumulator results in a better quality of shift of the 1-2 shift valveand extends the useful life of the transmission including the secondgear bands.

In a further embodiment of the present invention, the sealing assemblyof the factory installed RE4R01A automotive transmission is modified toprevent leakage and extend the useful life of the seal. The modificationto the factory installed sealing system includes mounting a wireretaining element around the outer surface of a seal element mountedaround the outer surface of a rotatable shaft to increase the inwardlydirected force applied to the seal pressing it against the shaft, and tocounteract centrifugal forces applied to the seal tending to displacethe seal away from the shaft as the shaft rotates.

In a further embodiment of the present invention, the hydrauliccircuitry of a factory installed 4R44E/4R55E automotive transmission ismodified to provide a smooth, quick and forward clutch apply circuitthat is reliable and is controlled exclusively by movement of the shiftcontrol lever and not by the power train control module, the EPCregulating solenoid, the availability of the forward modulator valve toregulate a forward engagement control valve, or the ability of a forwardclutch circuit to rapidly attain a pressure of 40 psi. The hydrauliccircuitry of the factory installed 4R44E/4R55E automotive transmissionis further modified to increase servo apply pressure to the intermediateand overdrive servos for increasing the holding capacity of the secondand fourth gear bands and to provide means for adjusting the feel of theshift (e.g., soft or firm) to suit a particular driver or vehicle, asdesired.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1A-1D illustrate a diagram of the hydraulic circuitry of a factoryinstalled TFOD-DSL automotive transmission, modified in accordance withthe present invention;

FIGS. 2A-2D illustrate a diagram of the factory installed RE4R01Aautomotive transmission, modified in accordance with the presentinvention;

FIG. 3A illustrates the sealing assembly for the direct inner clutchemployed in the factory installed RE4R01A automotive transmission, andFIG. 3B illustrates improvements to that sealing assembly in accordancewith the present invention; and

FIG. 4 illustrates the hydraulic circuitry of the factory installed4R44E/4R55E automotive transmission, modified in accordance with thepresent invention.

DESCRIPTION OF THE BEST MODES FOR CARRYING OUT THE INVENTION

FIGS. 1-4 of the drawing illustrate improvements to automotivetransmissions in accordance with the present invention. Theseimprovements include modifications to the hydraulic circuitry of thefactory installed transmissions to improve the efficiency andperformance of the transmissions, and modifications to the sealingassembly of factory installed automotive transmissions to reduce orprevent leakage of transmission fluid and avoid damage to thetransmission resulting from such leakage.

Referring to FIGS. 1A-1D, the hydraulic circuitry of a factory installedTFOD-DSL automotive transmission, as modified in accordance with thepresent invention, is illustrated. The operation of this factoryinstalled transmission is well known to those skilled in the automotivetransmission art, and will not be discussed in detail herein. Inaccordance with the present invention, a regulator valve designated byreference numeral 2 feeds main line pressure to a throttle valve,designated by reference numeral 4. A pressure regulator spring,designated by reference numeral 6, applies a resilient force againstmovement of the regulator valve in a leftward direction as viewed inFIG. 1C. In the factory installed transmission, the regulator spring 6is selected to produce a main line pressure of 95 pounds per square inch(psi), which is fed via the hydraulic circuitry of the transmission, tothe throttle valve 4. Operation of the transmission at a main linepressure of 95 psi results in insufficient torque capacity causingslipping of gears and soft shifts when the vehicle engine is operatingnear maximum capacity (e.g., wide open throttle). Increasing the mainline pressure will correct the gear slippage problem, but may causeundesirable side effects including late shifts or no upshifts duringwide open throttle operation.

In accordance with the present invention, the hydraulic circuitry of theTFOD-DSL automotive transmission is modified to increase the mainlinepressure, but to also make additional adjustments to avoid any potentialundesirable side effects. The pressure regulator spring 6 of the factoryinstalled transmission is replaced with a stronger pressure regulatorspring to result in a main line pressure of 120 psi or greater fed fromthe regulator valve 2 to the throttle valve 4. Accordingly, the mainline pressure at wide open throttle conditions is 120 psi or greater,thereby preventing the undesireable side effects of gear slippage andsoft shifts when the engine is operating near maximum capacity (i.e.,near wide open throttle operation). The hydraulic circuitry is furthermodified to avoid any undesirable side effects, such as late shifts orno upshifts during wide open throttle operation, resulting from theincrease in maximum main line pressure. In the factory installedtransmission, throttle valve pressure delays shifting. A plunger, shownas kickdown valve 10, acts on a throttle valve spring designated byreference numeral 8, which in turn drives the throttle valve 4. Fromapproximately light throttle operation to about ⅞th full throttleoperation, line pressure is regulated by continually increasing thecompression of the throttle valve spring 8 resulting from the leftwardmovement of the kickdown valve 10 in the direction shown in FIG. 1Cwhich continually increases the resilient force applied to the throttlevalve by the throttle valve spring.

At engine operation above ⅞th throttle condition, the left end of thekickdown valve 10 directly contacts the right end of the throttle valve4, thereby preventing any further increase of the resilient forceexerted by the throttle valve spring on the throttle valve, as thethrottle valve continues to be driven leftwardly by the kickdown valve.

In order to avoid this problem, the factory installed TFOD-DSL ismodified so that the size of the throttle valve relative to the kickdownvalve is adjusted so the kickdown valve will not directly engage thethrottle valve even at engine operation above ⅞th full throttlecondition. Preferably, this modification is accomplished by shorteningthe length of the throttle valve of the factory installed automotivetransmission. In this manner, the throttle valve spring exerts acontinually increasing resilient force on the throttle valve, even nearwide open throttle operation.

Therefore, in accordance with one aspect of the present invention, thefactory installed TFOD-DSL automotive transmission is modified toincrease main line pressure to avoid slipping of gears and soft shiftsduring engine operation near wide open throttle conditions, and isfurther modified to prevent undesirable side effects including lateshifts and no upshift at wide open throttle by adjusting the relativesizes of the throttle valve and the kickdown valve such that acontinuously increasing resilient force is applied to the throttle valveby the throttle valve spring throughout the operating range of thevehicle engine including wide open throttle operation.

FIGS. 2A-2D of the drawing illustrates a further aspect of the presentinvention in which the hydraulic circuitry of the factory installedRE4R01A automotive transmission is modified in accordance with thepresent invention. The operation of this factory installed transmissionis known to those skilled in the automotive transmission art, and willnot be discussed in detail herein. In the factory installedtransmission, the maximum accumulator pressure is approximately 70 psi(pounds per square inch). However, the Applicant has recognized that anincrease in the range of accumulator pressure will result in animprovement in the quality of the shift of the 1-2 shift valve and willextend the useful life of the second gear bands of the automotivetransmission.

In accordance with the present invention, the range of accumulatorpressure is extended from 70 psi in the factory installed transmissionto 150 psi. This is accomplished by modifying the 1-2 accumulator,designated by reference numeral 12, to remove an upper seal from thesecond accumulator piston, designated by reference numeral 14 in FIG.2B, and by plugging an exhaust opening, designated by reference numeral16 in FIG. 2B, in the 1-2 accumulator 12 of the factory installedautomotive transmission. In this manner, line pressure is applieddirectly to the 1-2 accumulator, increasing the pressure range of theaccumulator from 70 psi to 150 psi. Additional adjustments to theincreased accumulator pressure range can be accomplished by installingone or more high rate springs to replace the seal removed from the 1-2accumulator to exert a resilient force on the 1-2 accumulator.

Extending the pressure range of the 1-2 accumulator results inimprovement to the quality of the shift between first and second gear,and increases the useful life of this factory installed automotivetransmission.

FIG. 3A illustrates a sealing assembly of the type employed in thefactory installed RE4R01A automotive transmission. A piston 18 partiallyencloses a seal element 20 and exerts an inwardly directed force on theseal towards an outer surface 22 of a rotatable shaft 24. As a result ofuse, time, temperature and centrifugal forces applied to the seal 20 bythe rotating shaft 24, the seal tends to expand outwardly, allowingclearance between the seal and the outer surface 22 of the shaft 24.This clearance results in leakage of fluid, causing slipping of theclutch plate and burnup resulting in the loss of third or fourth gear,and further resulting in serious contamination of the hydrauliccircuitry of the automotive transmission as a result of the shredding ofthe clutch plate friction material.

FIG. 3B illustrates improvements to the sealing assembly of the factoryinstalled transmission illustrated by FIG. 3A. In the improvementillustrated by FIG. 3B, one or more retaining elements, preferablycontracting wires 26, are disposed between the outer surface of the sealelement 20 and an inner surface of the portion of the piston 18 in whichthe seal element is received. The contracting wire 26 extends around theouter surface of the seal element 20, and exerts an inward force urgingthe inner surface of the seal element to remain in contact with theouter surface 22 of the rotatable shaft 24. Preferably, the seal isformed from Teflon which is relatively harder and less prone todeformation and wear than typical rubber seals. Also, the seal ispreferably formed with an inner diameter that is slightly smaller thanthe outer diameter of the shaft to assure a contiguously abuttingrelationship between the inner surface of the seal element and the outersurface of the shaft when the seal is initially mounted around theshaft.

The contracting wires 26 exert an inwardly directed force on the seal tomaintain firm contact between the inner surface of the seal and theouter surface of the shaft, and to counteract a portion of thecentrifugal force tending to cause the seal to expand outwardly when theshaft is rotated. If any fluid is received in the space between thepiston and the seal which accommodates the contracting wire 26, suchfluid tends to exert a pressure inwardly against the outer surface ofthe seal element, thereby supplementing the inwardly directed forceprovided by the contracting wire 26 to maintain the seal abuttingagainst the outer surface of the shaft in sealing relationship.

FIG. 4 illustrates the hydraulic circuitry of a factory installed4R44E/4R55E automotive transmission, as modified in accordance with afurther aspect of the present invention. The operation of this factoryinstalled transmission is known to those skilled in the automotivetransmission art, and will not be discussed in detail herein. Theoriginal hydraulic circuitry for this factory installed transmission isdesigned such that when the shift control lever is placed into the driveposition, the power train control module activates the EPC (electronicpressure control) solenoid to deliver approximately 30 psi (pounds persquare inch) of EPC pressure to the right side of the forward modulatorvalve designated by reference numeral 28 in FIG. 4. This applied fluidpressure moves the valve 28 in a leftward direction, as seen in FIG. 4,against the urging of a spring, and differential in valve land diametersallows line pressure to enter the forward modulator circuit. Forwardmodulator oil then travels to the forward engagement valve, designatedby reference numeral 30 in FIG. 4, via line 32. The fluid pressureapplied to the forward engagement valve acts on the differential of thevalve, moving it in a rightward direction as seen by FIG. 4 against theresilient force of a spring to slowly apply the forward clutch,designated by reference numeral 34 in FIG. 4. Once 40 psi is obtained inthe forward clutch, the forward engagement control valve 30 will moverightward sufficient to allow line pressure into the forward clutchcircuit through line 31 to shut off the flow of forward modulator oil.This results in forward movement of the vehicle.

The hydraulic circuitry of the factory installed transmissions discussedabove include certain operating disadvantages. The forward movement ofthe vehicle relies on a power train control module, approximately thirty(30) feet of wiring, the ability of the EPC solenoid to regulate, theability of the forward modulator valve, the ability of the forwardengagement control valve to move, and the ability of the forward clutchcircuit to quickly obtain a pressure of 40 psi. Failure of any of thecomponents to perform will result in loss of forward movement of thevehicle. In accordance with a further aspect of the present invention, aplug designated by reference numeral 36 is provided to block the flow offorward modulator oil from the forward modulator valve 28 to the forwardengagement control valve 30. A fluid flow passageway designated byreference numeral 38 is provided to permit line pressure to directlyenter the forward clutch 34 through line 31 to quickly increase thepressure in the forward clutch circuit. The increased pressure also actson the differential of land diameters on the forward engagement controlvalve 30, moving it in a rightward direction, as seen in FIG. 4, againstthe force of a spring to allow the full flow of line pressure into theforward clutch 34. This modification to the hydraulic circuitry of thefactory installed automotive transmission results in a smooth, quick,positive and reliable means of selecting forward movement of theautomatic transmission. The modification to the factory installedautomotive transmission also provides a system by which the forwardclutch apply circuitry is reliable and is controlled strictly bymovement of the shift control lever.

Still referring to FIG. 4, the hydraulic circuitry of the factoryinstalled 4R44E/4R55E automatic transmission is also modified toincrease servo apply pressure to the intermediate and overdrive servos,to increase the holding capacity for the bands for the second and fourthgears, and to provide a mechanic with means to adjust the feel of theshift (e.g., soft or firm) to suit any particular driver or vehicle.This improvement is accomplished by providing an end plug and spring,designated by reference numeral 40 in FIG. 4, on the right end of theforward modulator valve 28. The end plug includes a hollow portion foraccommodating a spring, and the spring acts on the right side of theforward modulator valve 28, as seen on FIG. 4. The resilient forceexerted by the spring supplements the EPC fluid pressure 42 tending tomove the forward modulator valve 28 in a leftward direction as seen onFIG. 4, thereby increasing the regulated servo apply oil pressure to theintermediate servo and the overdrive servo for producing faster andfirmer upshifts and increasing the holding capacity of the intermediateand overdrive bands, as designated by reference 44 in FIG. 4. An orificedesignated by reference numeral 46 in FIG. 4, which can be provided by asmall aluminum bushing (having a 0.042 diameter feed hole), is installedin the apply circuit at the input to the intermediate band and servo 48to insure smooth servo reapply during a closed throttle 3-2 coastdownshift. Adjustment of the feel of the shift (softer or firmer) isaccomplished by selecting the appropriate spring corresponding to thedesired shift feel, and installing the selected spring in the hollow endplug 40 at the right end of the forward modulator valve 28, as seen onFIG. 4.

Other modifications within the scope of the present invention willbecome apparent to those skilled in the art. Accordingly, the abovediscussion of the preferred embodiments is intended to be illustrativeonly, and not restrictive of the scope of the invention, that scopebeing defined by the following claims and all equivalents thereto.

What is claimed is:
 1. A method of modifying the hydraulic circuitry ofa factory installed automotive transmission including a 1-2 accumulator,the steps of said method including: plugging an exhaust opening in said1-2 accumulator of said factory installed transmission to apply linepressure to said 1-2 accumulator to increase the accumulator pressureabove 70 pounds per square inch.
 2. The method as claimed in claim 1,wherein the step of plugging includes plugging an exhaust opening insaid 1-2 accumulator of said factory installed transmission to applyline pressure to said 1-2 accumulator to increase the accumulatorpressure to a range between above 70 pounds per square inch and 150pounds per square inch.
 3. The method as claimed in claim 1, wherein thestep of plugging includes the step of plugging an exhaust opening insaid 1-2 accumulator to apply line pressure to said 1-2 accumulator toincrease the accumulator pressure to at least 150 pounds per squareinch.
 4. The method as claimed in claim 1, including the step ofremoving a seal from a piston of said 1-2 accumulator of said factoryinstalled transmission to apply line pressure to said 1-2 accumulator.5. The method as claimed in claim 4, wherein said 1-2 accumulator ofsaid factory installed transmission has upper and lower seals, and saidstep of removing includes removing said upper seal.
 6. The method asclaimed in claim 4, including the step of replacing said seal removedfrom said piston of said 1-2 accumulator with a spring for exerting aresilient force on said 1-2 accumulator.
 7. The method as claimed inclaim 5, including the step of replacing said upper seal removed fromsaid piston of said 1-2 accumulator with a spring for exerting aresilient force on said 1-2 accumulator.